Burmochlamys fasciola Pholyotha & Panha, 2022

Pholyotha, Arthit, Sutcharit, Chirasak, Lin, Aung & Panha, Somsak, 2022, Uncovering local endemism from southeastern Myanmar: description of the new karst-associated terrestrial snail genus Burmochlamys (Eupulmonata, Helicarionidae), ZooKeys 1110, pp. 1-37 : 1

Burmochlamys fasciola Pholyotha & Panha sp. nov.

Figs 1 , 2A , 3A , 5A , 7C, D , 8J-L , 10A , 11D

Material examined.

Type material. Holotype: CUMZ 14213 (Fig. 7C ; width 5.6 mm, height 5.1 mm). Paratypes: Same locality as holotype: CUMZ 14214 (Fig. 7D ; width 5.8 mm, height 4.9 mm), NHMUK (two shells).

Other material.

Kyankaw Mountain , Hpa-An, Kayin State, Myanmar (17°00'59.5"N, 97°42'12.4"E): CUMZ 14215 .

Type locality.

Bardai Mountain, Hpa-An, Kayin State, Myanmar (17°00'00.5"N, 97°41'41.6"E).

Diagnosis.

Shell globose and milky white with narrow yellowish brown band. Animal pale freshy-grey with five mantle extensions. Genitalia with rather short epiphallic caecum attached by thin penial retractor muscle, very short vagina, and solid at the tip of dart apparatus.

Description.

Shell (Figs 7C, D , 8J-L ). Shell globose, small (width up to 6.1 mm, height up to 6.0 mm), thin, semi-translucent. Colour milky-white with a narrow yellowish brown band above periphery. Protoconch and teleoconch surface with similar sculpture. Surface of body whorl with distinct spiral furrows at regular intervals, cut by distinctly undulating radial lines (Fig. 8J-L ). Whorls 6- 6½, increasing regularly; suture shallowly impressed; spire much elevated; last whorl well-rounded. Aperture obliquely crescent-shaped; peristome simple. Columellar margin simple, slightly reflected near umbilicus. Umbilicus open, narrow, and deep.

Genital organs (Fig. 10A ). Atrium (at) very short or indistinct. Penis (p) moderate, cylindrical and with a thin penial sheath. Epiphallus (e1+e2) ca. three-fifths of penis length; e1 cylindrical and smaller diameter than penis and e2; e2 bulbous and ca. half of e1 length. Epiphallic caecum (ec) rather short, cylindrical and with a thin penial retractor muscle (prm) attached at tip. Vas deferens (vd) thin tube. Dart apparatus large, long cylindrical, with solid at the tip (yellow arrow in Fig. 10A ), and located on atrium at vagina and penis junction. Vagina (v) very short to indistinguishable. Gametolytic sac (gs) bulbous; gametolytic duct (gd) cylindrical, moderate, slightly shorter than penis. Free oviduct (fo) ca. half of penis length, cylindrical, and encircled with thick tissue near vagina.

Radula (Fig. 11D ). Teeth arranged in wide U-shaped rows with each row consisting of ~ 50 teeth. Central tooth monocuspid, large and oblong spatulate plate, and attached by two smaller triangular-shaped teeth at its base. Laterals and marginals not differentiated and monocuspid; each tooth with large and oblong spatulate plate attached by only a smaller triangular-shaped tooth at base on outer side. From inner to outer, lateromarginal teeth gradually narrower, smaller, and rather more pointed cusp. Some outermost teeth with a small and pointed cusp at inner side.

External appearance (Figs 3A , 5A ). Living animal with reticulated skin and pale freshy-grey body. Five mantle extensions present, same colour as body. Sole divided into three parts longitudinally. Caudal foss (cf) and caudal horn (ch) present with similar colour to body.

Etymology.

The specific epithet is the Latin word fasciola meaning band or stripe. It refers to the presence of a brownish peripheral band, which characterises this species.

Distribution.

Burmochlamys fasciola sp. nov. is known from two limestone areas in the south of the Salween River basin (Fig. 1 ). The Bardai Mountain (Fig. 2A ) and Kyankaw Mountain are surrounded by paddy fields that are temporarily flooded during the monsoon season. In Kyankaw Mountain, this new species is sympatric with the limestone karst-restricted land snail species, Sophina salweenica .

Remarks.

The distinguishing characters of B. fasciola sp. nov. is a milky-white shell with a narrow yellowish brown peripheral band and rather elongated radular teeth. Whereas the other Burmochlamys species have a pale to dark brownish shell without any band and the radular teeth have a broad spatulate shape (see Table 2 ).

Figures

Figure 1. Map of the Salween River basin (known as Thanlwin River) in the southeastern Myanmar showing the sampling sites. Coloured triangles indicate the localities recorded for each Burmochlamys species. White circles indicate the localities recorded for Sophina species. White squares indicate the sampling localities with no records of both Sophina and Burmochlamys species.

Figure 2. Habitat of some species of Burmochlamys gen. nov. in the karst basin of Hpa-An, Kayin State, Myanmar. A type locality of B. fasciola sp. nov. at Bardai Mountain and microhabitat structure of the karst wall B newly discovered locality of B. poongee at Kaw Ka Thaung Cave C type locality of B. albida sp. nov. at Waiponla Monastery D type locality of B. moulmeinica sp. nov. at Lun Nya Pagoda E type locality of B. versicolor sp. nov. at Bayin Nyi Cave. Photos by Ruttapon Srisonchai.

Figure 3. Synoptic illustration of mantle extensions, body terminology and radular morphology of Burmochlamys gen. nov. A right and left shell lobes of B. fasciola sp. nov. B mantle extensions (shell lobes and dorsal lobes) and posterior body of B. poongee C dorsal view of mantle extensions (shell lobes and dorsal lobes) of B. cassidula D, E representative SEM images of radula showing monocuspid central tooth (yellow) and lateromarginal teeth (blue) attached by the smaller triangular-shaped teeth (red). White arrow indicates pneumostome or breathing pore. Yellow arrow indicates a tiny cusp on outermost lateromarginal teeth.

Figure 5. Living snails of Burmochlamys species A B. fasciola sp. nov. paratype CUMZ 14214 showing left and right lateral views B B. cassidula specimen CUMZ 14209 C B. poongee specimen CUMZ 14210 D B. albida sp. nov. paratype CUMZ 14212 E B. moulmeinica sp. nov. paratype CUMZ 14217 F B. versicolor sp. nov. paratype CUMZ 14219 G B. whitteni sp. nov. paratype CUMZ 14222.

Figure 7. Shells of Burmochlamys species A, B B. albida sp. nov. A holotype CUMZ 14211, and D paratype CUMZ 14212 C, D B. fasciola sp. nov. C holotype CUMZ 14213 D paratype CUMZ 14214 E, F B. moulmeinica sp. nov. E holotype CUMZ 14216 F paratype CUMZ 14217.

Figure 8. Representative SEM images of the shell of Burmochlamys species A-C B. cassidula specimen CUMZ 14209 A protoconch B body whorl C zoom-in view of body whorl D-F B. poongee specimen CUMZ 14210 D protoconch E body whorl F zoom-in view of body whorl G-I B. albida sp. nov. paratype CUMZ 14212 G protoconch H body whorl I zoom-in view of body whorl J-L B. fasciola sp. nov. paratype CUMZ 14214 J protoconch K body whorl L zoom-in view of body whorl.

Figure 10. General view of the genital system of Burmochlamys species A B. fasciola sp. nov. paratype CUMZ 14214 B B. moulmeinica sp. nov. paratype CUMZ 14217 C B. versicolor sp. nov. paratype CUMZ 14219. White arrow indicates the end of the penis. Yellow arrow indicates the solid at the tip of dart apparatus. Red-dotted line indicates vas deferens missing.

Figure 11. Representative SEM images of the radula of Burmochlamys species A B. cassidula specimen CUMZ 14209 B B. poongee specimen CUMZ 14210 C B. albida sp. nov. paratype CUMZ 14212 D B. fasciola sp. nov. paratype CUMZ 14214. Central tooth indicated by ' C'; yellow colour indicates central tooth row.